This invention relates to a system for detecting and compensating for the vibrational effect on a closure characteristic, in the detection of an object in the closure path.
Vehicles are provided with closures such as windows, sunroofs, moonroofs, etc. These closures are typically closed by a power motor at the control of an operator input button. For purposes of this Application, the term xe2x80x9cwindowxe2x80x9d will extend to not only windows, but also to moonroofs, sunroofs and other closures which are moveable within a frame in the vehicle.
With the advent of powered closures in vehicles, a problem arose in detecting the presence of an object in the path of a closure member. As an example, when a switch is actuated to move a closure member to a closed position, a passenger may have an arm in the frame opening. The arm would be contacted by the window. It is desirable for a motor control to detect the presence of this obstruction.
Typically, systems for detecting an obstruction have looked at a characteristic, (e.g., the speed, power or torque on the motor), and looked for the characteristic to exceed a predetermined limit. If the limit is exceeded, then a determination is made that an object is present.
However, these systems have been prone to identifying xe2x80x9cfalsexe2x80x9d obstructions under certain conditions. One problem with these systems is that the characteristics being monitored are sensitive to vibration. Thus, should the vehicle be driven over a rough road surface, vibration on the vehicle affects the monitored characteristic. If the vibrational effect is significant, the monitored characteristic could cross the predetermined limit, and a false obstruction could be sensed. Typically, if an obstruction is sensed, the control either stops or reverses the motor. It would be desirable to eliminate, or at least minimize false obstruction readings.
As an example, FIG. 1A shows a system wherein predicted motor speed 20 is shown over time. The actual motor speed 22 under the presence of vibration is shown having peaks 24 and 28 and corresponding valleys 26 and 30. Generally, the effect of vibration on the characteristics, such as speed, will have a peak and a corresponding valley. In a system monitoring speed, if the detected speed drops below a predetermined limit 32, then an obstruction is identified.
It should be understood that known vehicle window obstruction systems monitor other characteristics such as power or torque. For example, in a power system, the predetermined limit will be above the predicted power value. That is, an obstruction will cause power to increase. This invention extends to monitoring characteristics other than speed.
A reading 34 is indicative of the speed when an object is encountered. This reading crosses the predetermined limit 32 at point 36. At point 36, the control for the system 19 identifies an obstruction and reverses the motor, or stops the motor.
As shown schematically in FIG. 1B, a motor 21 is powered by a control 19 to drive a closure member 23 into a frame 25. During this movement, the control 19 monitors a characteristic, such as motor speed, and identifies an obstruction based upon the monitored characteristic crossing predetermined limit 32.
However, a vibration caused valley, such as valley 30, which is deep enough, might also cross the predetermined limit 32. In such a case, the control 19 would identify struction in the path of the closed and would stop a reverse operation of the motor. This would be undesirable.
In a disclosed embodiment of this invention, a control looks for a change in a monitored characteristic in a direction opposed to the direction indicative of an obstruction. In a speed monitored system, this would mean a speed movement above the predicted speed. A speed above the predicted speed would not be indicative of an obstruction. Thus, the system assumes that such an increased speed is indicative of a vibration effect. The system determines the value of the movement above the predicted value, and may then multiply that value by a scaler value. The real value of the scaler times the amount above the speed value is then utilized as a correction below the speed value. The correction is held over a period of time to cancel out the upcoming expected valley in the speed value due to the vibration and its reaction. The compensation decays over time back toward zero. The compensation can alternatively be used to adjust the limit rather than the expected value.
In this way, the predicted speed value, or the limit, is modified to compensate for the effect of vibration. Should an obstruction be detected, the limit will still be crossed; however, the crossing will not be due simply to a vibration caused valley in the speed value. In this way, false identifications of an obstruction are eliminated or minimized.
As a refinement, the values at start up of window movement may be ignored for this invention. A high speed value is expected at start up and would not be indicative of vibration. Thus, a delay may be programmed into the control before the inventive vibration monitoring begins.
These and other features of the present invention can be best understood from the following specification and drawings.